<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        /* function Fun() {

            console.log(this);

            this.name = "lili";

            var age = 18;

            this.test = function () {

                console.log(this.age);

                console.log(age);

                var age = 20;
            }
        }

        var f = new Fun();

        console.log(typeof f);

        console.log(typeof f.test()); */

        console.log(10 > 5 && 12 == "12");
        console.log(12 + "12" || 10 > 100);
        console.log(undefined || null);

        console.log(100 - 120 || 10 - 10);
        console.log(10 - 10 && 100 - 120);

    </script>
</body>

</html>